PSI - Issue 5

ScienceDirect Available online at www.sciencedirect.com Av ilable o line at ww.sciencedire t.com cienceDirect Structural Integrity Procedia 00 (2016) 000 – 000 Procedia Structu al Integrity 5 (2017) 745–752 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2017) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2017) 000 – 000

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XV Portuguese Conference on Fracture, PCF 2016, 10-12 February 2016, Paço de Arcos, Portugal Thermo-mechanical modeling of a high pressure turbine blade of an airplane gas turbine engine P. Brandão a , V. Infante b , A.M. Deus c * a Department of Mechanical Engineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisboa, Portugal b IDMEC, Department of Mechanical Engineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisboa, Portugal c CeFEMA, Department of Mechanical Engineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisboa, Portugal Abstract During their operation, modern aircraft engine components are subjected to increasingly demanding operating conditions, especially the high pressure turbine (HPT) blades. Such conditions cause these parts to undergo different types of time-dependent degradation, one of which is creep. A model using the finite element method (FEM) was developed, in order to be able to predict the creep behaviour of HPT blades. Flight data records (FDR) for a specific aircraft, provided by a commercial aviation company, were used to obtain thermal and mechanical data for three different flight cycles. In order to create the 3D model needed for the FEM analysis, a HPT blade scrap was scanned, and its chemical composition and material properties were obtained. The data that was gathered was fed into the FEM model and different simulations were run, first with a simplified 3D rectangular block shape, in order to better establish the model, and then with the real 3D mesh obtained from the blade scrap. The overall expected behaviour in terms of displacement was observed, in particular at the trailing edge of the blade. Therefore such a model can be useful in the goal of predicting turbine blade life, given a set of FDR data. 2nd International Conference on Structural Integrity, ICSI 2017, 4-7 September 2017, Funchal, Madeira, Portugal Fatigue strength and fracture mechanics U. Zerbst a *, M. M dia a and M. Vormwald b Bundesanstalt für Materialforschung und -prüfung (BAM), 9.1, Unter den Eichen 87, D-12205 Berlin, Germany b Technische Universität Darmstadt, Materials Mechanics Group, Franziska-Braun-Str. 3, D-64287 Darmstadt, Germany If fracture mechanics shall b applied to the total lifetime respectively the fatigue limit of components (within the meaning of the S-N curve approach) it has to address four challenges: (a) It has to adequately describe so-called short crack propagation, which cannot be based on the common long crack concepts for principle reasons. Since the crack size is in the order of the plastic zone size, the modelling of short crack propagation cannot be based on the common linear elastic  K concept. Instead, an elastic-plastic parameter such as the cyclic J integral has to be applied. A second point is that the crack closure concept has to be modified in that the crack opening stress is not a constant, crack size independent parameter but shows a transient behaviour with increasing short crack size. (b) It has to provide a meaningful definition of the initial crack dimensions as the starting point for an S-N curve relevant (residual) lifetime analysis. This can be based either on the (statistical) size of material defects which can be treated as cracks or by the size of the crack which would arrest subsequent to early crack propagation, whatever is larger. (c) It has t cope with the problem of mu tiple r cks for lo d levels higher than the fatigue limit such s it occurs in many applications in the absence of very large initial defects. (d) This requires consequent statistical treatment taking into account variations in the local geometry of the area where crack initiation has to be expected as well as the scatter in the initial crack size and in the material data used for the analyses. 2nd International Conference on Structural Integrity, ICSI 2017, 4-7 September 2017, Funchal, Madeira, Portugal Fatigue st ength and fracture mechanics U. Zerbst a *, M. Madia a and M. Vormwald b Bundesanstalt für Materialforschung und -prüfung (BAM), 9.1, Unter den Eichen 87, D-12205 Berlin, Germany b Technische Universität Darmstadt, Materials Mechanics Group, Franziska-Braun-Str. 3, D-64287 Darmstadt, Germany Abstract If fracture mechanics shall be applied to the total lifetime respectively the fatigue limit of components (within the meaning of the S-N curve approach) it has to address four challenges: (a) It has to adequa ely describe so-called short crack pr pagation, whic ca not be based on the common long crack concepts f r principle reasons. Since the crack size is in the ord r of the plastic zone size, the modelling of short crack propagation cannot be b sed on the common lin ar elastic  K concept. Instead, an elastic-plastic paramet r such as the cyclic J i tegral h s to be a plied. A second point is that the crack closure concept has t be modif ed i that the crack ope ing stress is not a const nt, cr ck size independent parameter but shows a transient behaviour with increasing short crack size. (b) It has to provide meaningful definition of the initial crack imensions as the starting point for an S-N curve relevant (residual) lifetime analysis. This can be based either on the (statistical) size of material defects which can be treated as cracks or by the size of the crack which would arrest subsequent to early crack propagation, whatever is larger. (c) It has to cope with the problem of multipl cr cks for load levels higher than the f tigue limit such s it occurs in many applications in the absence of very large i itial defects. (d) This requires consequent statistical treatment taking into account variations in the local geo etry of the area where crack initiation has to be expected as well as the scatter in the initial crack size and in the material data used for the analyses. Keywords: Fatigue strength; fracture mechanics; initial crack size; short crack propagation; multiple crack propagation © 2017 The Authors. Published by Elsevier B.V. Peer-review und r responsibility f the Sci nt fic Committe of ICSI 2017 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. Keywords: Fatigue strength; fracture mechanics; initial crack size; short crack propagation; multiple crack propagation Introduction: Fatigue strength as crack arrest phenomenon During its lifecycle a fatigue crack experiences different stages of propagation, Fig. 1(a). Usually a large number of microstructu rally short cracks is initiated within the microstructur but most of them will be arrested, e.g. at grain boundaries or other obstacles. Keywords: High Pressure Turbine Blade; Creep; Finite Element Method; 3D Model; Simulation. Introduction: Fatigue strength as crack arrest phenomenon During its lifecycle a fatigue crack experiences different stages of propagation, Fig. 1(a). Usually a large number of microstructu rally short cracks is initiated within the microstructure but most of them will be arrested, e.g. at grain boundaries or other obstacles. Abstract

2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. 2452-3216  2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ICSI 2017 10.1016/j.prostr.2017.07.165 2452-3216 © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ICSI 2017. 2452 3216 © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ICSI 2017. * Corresponding author. Tel.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt * Corresponding author. Tel.: +49 (0) 30 8104 1531; fax: +49 (0) 30 8104 1537. E-mail address: uwe.zerbst@bam.de * Corresponding author. Tel.: +49 (0) 30 8104 1531; fax: +49 (0) 30 8104 1537. E-mail address: uwe.zerbst@bam.de